Chlorine is used in spas to sanitize the water. It kills bacteria, algae and other harmful microorganisms. It also combines with ammonia and nitrogen from body oils and sweat. Free chlorine levels are recommended to fall between 1.5 and 3ppm. After the spa is super-shocked to break up contaminants, chlorine levels can be as high as 8 to 10ppm. You should not use spas until the levels drop back to the normal range.
Remove the spa cover and allow the chlorine to dissipate into the air.
Allow sunlight to contact the spa water. Ultraviolet radiation breaks down chlorine.
Wait 24 hours. Chlorine levels decrease as it combines with contaminants.
Drain a portion of the water and replace it with fresh water if chlorine levels remain elevated.